"As of 31 May 2010, waters from Changi Naval Base to East Coast Park were clear of any oil patches," said the Maritime and Port Authority of Singapore (MPA) in a press release issued Monday evening.
Oil patches which had drifted into Malaysian waters were also being cleaned up, said the Malaysian Maritime Enforcement Agency (MMEA).
"Clean-up efforts are under way and based on our assessments, it will be completed in three days," an MMEA spokesman told AFP.
No new oil patches had drifted into Malaysian waters since Sunday, Singapore's MPA added.
"We did not receive any further reports or sightings of oil patches in Malaysia waters off Tanjong Pengelih today," an MPA spokeswoman told AFP.
On Sunday, the MPA said patches of oil had been sighted off Tanjong Pengelih in southern Malaysia and waters off Singapore's eastern coast.
The spill came from the Malaysian-registered MT Bunga Kelana 3, a tanker carrying 62,000 tonnes of crude when it collided last Tuesday off Singapore with the MV Waily, a bulk carrier registered in St Vincent and the Grenadines.
About 2,500 tonnes of crude leaked from a gash in the double-hulled tanker but most of it was contained at sea, according to the MPA.
Singapore is a compact island republic known for its strict environmental standards, but the heavy maritime traffic off its coasts makes it vulnerable to the effects of shipping disasters.